Expansion arbor



Sept. 3o, 1952 H. WOLLNER 2,612,376

EXPANSION ARBOR Filed Feb. 2, 1946 2 SHEETS-SHEET lA INVENTOR 'HJM/.5 WONE'R will! H. WOLLNER EXPANSION ARBOR slept. so, 1952 2 SHEETS- SHEET 2 Filed Feb. 2, 1946 ATTORNEY Patented Sept. 30, 1952 EXPANSION Anson Hans WollnenDetroit, Mich., assigner yto Yinco Corporatiom Detroit, Mich., a corporatonof Michigan Application February 2, 1946, SerialNo. 645,145

V'This inventionfrelates to improvements in expansion '.arbors for .attaching machine parts to rotating spindles. The invention is particularly useful in the-manufacture" of vmachinepartsvfor attaching the Work Apieces to be-shaped to vthe spindles of machine tools or .grinding machines by Whichthey are supported and rotated While being shapedby the'tool or grinding wheel. In the manufacture of gears, vioraexample, itis necessary that .thefblank ibe vcentered with extreme accuracy on thexrotatingspindle ofthe machine tool or. grinder, by means. of `which the teeth are formed or nished. It lis .also-.necessary that the gears .be made with .smooth-finished, accurately centered shaft;openings so that they may be accurately .splined for their-.attachment to y,the shaft .of v.the machineiin'fvfhichthey are to-.loe used. 1 f The'attac'hment .of Work pieces toV the-spindles' of machine tools `has 'heretofore been accomplished in various Ways all of Which, however,'.to my knowledge, rhave resulted'in an yunbalanced pressure uponfthe metal ofxtheV Work .pieceso that when the. work. piece is removed from the'spindle it Willbe-.out :of tit-neto; an amount to be `signin-A cant vWhere.close.manuiacturing tolerances must be met, andtheprimarypobject of 'this invention is to provide an expansion arbor 'by means `of which a workpiece ymay-loe-rmly attached to a rotating.l spindle lso that it1 is'accurately centered with-respect to thepaxis of. rotation 4of the spindle andis .not:;s11bje.cted toany unbalanced pressure throughout itsentre circumference.

.A :further objectef the invention -is` to provide an-'Iexpansion arborby means of which 1.a Work piecezana-yA beuuickly attached to and detached ironflfthe.spindle by Whiehitzis to -be rotated. .Aiurtiier oibjectlof .theinvention is to provide 9 claims. (el. 2mg-2) its entire` outer circumference with longitudinal anexpansionfarbor-.of general .application for attackling-parts to rotating .spindles which 'is of low manufacturing cost, which may be readily manufactured in various sizes,. and which is adapted for use either `as -atemporary or vpermanent con- ,'Fig. 5 is a longitudinal sectional' view'of' al modified form of the arbor-expanding' mechanism; and

Fig. ll6 is a .sectional view on linef-GF-B of Fig. 5.

Incthe drawings, I` indicates the frame ofthe machine on which Vissupported by means-eta bearing, not shown, `a rotating spindlej2. f The spindle 2 is provided witha tapered portion v3 .to which the workpiece, indicatedat 4,'1is` at'- tached; .Between :the workpiece-'ll` and the tapered portion 3 of Athespindle is a sleeve 5v' whos-e inner bore is tapered `tont thespindle and Whose outer cylindrical ysurface isv linished to havea snug sliding llit in .the bore of thevvork piece. This; sleeve is made'of steel or othersuitable ma- `teria-l having a reasonably. high coelcient'of elasticity. The Vsleeve 5 is provided throughout waythrough the thickness of thesleeve. The s grooves 'l arestaggered with respect tothe-groove 6 as A.shown 'in .Fig.y2, .so that the sleeve is symyrnetrical through .its circumference and when subjected to radial pressure .either inwardly o'r outwardly, will lcontract or expandeto a limited degree'andgstill maintain its exact symmetry with respect to its axis. 1 1

Any suitable means maybe employed,V to lexert longitudinal pressure on the sleevevfto-effect' its expansion and contraction. I have'illustrated for the purpose a pilot nut-8'threadedfon1anex- .tension 9 ofthe spindlerZ -beyond` the tapered portion y3. This pilot nut s'formed-with a shoulder lil vwhichengageszthe end face vof the sleeve S-and serves onrotation of the nutWith-respect tothe spindle to force the .sleeve to theleft, as shown inFig. 1, and thereby effect itsuniform expansion Within the bore of the 'Work piece 4. For shifting thesleeve in the vopposite direction-to contract theasleeve .and/release the :work piece l the pilot nut ,8131s provided-with areduced" portion Il. at its end adjacent the-tapered portion f3' of thev spindle, and mounted on this reduced portion of ,the nut 18,. preferably .by means cfa lefthand thread, is ,a collar /I2 which -engagesthe face of an( inward-ly .extendingflang'e l 3` formed on the end of theslee-ve-S adjacent 'theinutd The eel-lar l2 is attached to' the :mit*8before sleeve -5 isassembled on the tapered portion of`v the spindle may be similarly provided with opposite fiat faces Aon the other side of the tapered portion 3,y to facilitate holding the spindle when the nut 8 is turned on its thread to loosen or tighten the sleeve yin the Work piece.

In the embodiment shown in Figs. 1, 2 and 3, thereare sixteen outside grooves 6 and sixteen inside grooves 7, hence with an expansion at each groove of an extent too small to be independently measured the arbor may be expanded from a diameter where the work piece is freely rotatable on the arbor to an extent sufcient to hold'the work piece firmly and exactly in position on the spindle. Furthermore, even though the resistance to expansion may be greater in one portion of the metal of the sleeve than-in some otherv portion, the sleeve will nevertheless expand uniformly for the reason that the friction between the sleeve and the tapered portion of the spindle is such as to counteract any tendency to rotary movement of the sleeve during its expansion.

In Fig. 4 I have illustrated a somewhat modied form of arbor which is particularly useful where the torque to be transmitted from the arbor to the workpiece is not great. As here shown the expansible arbor I5 is provided withA a series of deepv grooves I'I'on its inner surface and with alternatinggrooves IB on its outersurface, the grooves' i6 being shallower than the grooves Il and with projections I3 between the grooves I6 of generally trapezcidal cross section. All the projections I3 except three at equally spaced points andA designated in the drawings Ilia,V

` y tion is that there is much less frictional resistance to the-longitudinal movement of the expansible arbor with respect to the spindle and the work piece. It is frequently 'desirable that the work piece be positioned at aidenite axial point on the spindle, and that with the expansible arbor of Fig. 4 the Work piece can be readily held against axial movement while the arbor is shifted longitudinally to expand the arbor to effect a driving engagement between the spindle and the work piece. f

The arbor of Fig. 4 also has the advantage that only the three projections |811, |8b and lchave to be finished Within small dimensional tolerances to secure an accurate positioning of the work piece. The intervening portions of the arbor Which do not contact the work piece provide in eect expansible connections between the three projections |8a, lBb andV IBC but as these intervening portions of thearbor do not contactthe` n form of my invention. As here shown the spindle 4 20 has a tapered portion 2l'near the outer end and beyond the rtapered portion has a reduced portion 22 which may be square or hexagonal and on which isl mounted for sliding movement a conical piece 23 having a tapered exterior surface corresponding with the surface of the portion 2|. The spindle 20 is threaded as shown to receive a screw 24 whose head bears against the hub of the conical piece 23. The expansible arbor 25 as here shown consists of a continuous ring having a Series of spaced interior slots 26 and a series of spaced exterior slots 21. The bore of the arbor is oppositely tapered at each end to fit, respec-l tively, the taperedportion of the spindle and the outer surface of the conical piece 23. The outer surface of the arbor between the longitudinal slots may be shaped throughout to fit the bore of the workpiece but preferably the metal is cut away y in the middle portion and at the end as indicated at 2S so that the arbor engages the bore of the work piece at two axially spaced locations, thereby reducing the friction between the arbor and the work piece, at the same time providing suiiicient driving connection and accurate centering of the workpiece with respect to the axis of rotation ofthe spindle. i,

In practiceit has been demonstrated thatpieces which have been shaped While mounted yon a spindle with the expansion arbor embodying my invention are not subject to distortion, and no change in shape can be ldetected by the most delicate instrument when the work pieces are removed from the'spindle.

It is of course to be understood that the construction shown in the drawingr and described above may be variously modified without departing from the spirit of theinvention. For example, the outer surface of the sleeve may be tapered instead of the inner surface, r,particularly if the work piece has a tapered bore. Any suitable'meansmay be used for shifting the tapered arbor for effecting a relatively longitudinal movement of the tapered arbor and the cooperating .tapered member. Also the arrangement of grooves in the inner and outer surfaces of the arbor need not be of the exact arrangement illustrated. 'Itis essential that a plurality of grooves be provided in the tapered surface so that the sleeve may be expanded by the relative longitudinal movement of the two tapered parts. It is also essential that the plurality of grooves be provided in the other surface of the sleeve so that it likewise may expand and contract, but the exact design and arrangement of the grooves, while preferable, is not essential to securing a flrm,vaccurately centered connection between the workpiece and the arbor. It will therefore be understood that the invention is not limited to the features of construction shown except insofar as such Vfeatures are enumerated in the appended claims. f

I claim:

1. In an expansion arbor, an expansible lelement including a` length of continuous sleeve having a series of spaced longitudinal grooves the length of its outer surface and a series of spaced longitudinal grooves the length ofits inner surface, the grooves of both series extending to a depth less than the thickness of the sleeve, one surface being axially tapered.

2. In an expansion arbor, an expansible element including a length of continuous sleeve having a series of uniformly spaced longitudinal grooves the length of its outer surface and a series of uniformly spaced longitudinal grooves the length of its inner surface, the grooves of both series extending to a depth less than the thickness of the sleeve, one surface being axially tapered.

3. In an expansion arbor, an expansibleelement including a length of continuous sleeve having a series of spaced longitudinal grooves the length of its outer surface and a series of spaced longitudinal grooves the length of its inner surface, one surface being axially tapered. said grooves having a depth of substantially one half the thickness of said sleeve.

4. A spindle and means for fastening a piece thereto comprising an expansible sleeve having a portion of its bore tapered and fitted on a tapered portion o f said spindle, a series of longitudinal grooves in the inner surface of said sleeve, a series vof external longitudinal grooves in the outer surface of said sleeve the grooves of both series extending to a depth less than the thickness of the sleeve, the outer diameter of the spindle being of a dimension determined by the bore of the work piece, and means mounted on the spindle for shifting said sleeve longitudinally thereof in opposite directions to expand and contract said sleeve.

5. A spindle and means for fastening a piece thereto comprising an expansible sleeve having a portion of its bore tapered and fitted on a tapered portion of said spindle, a series of 1ongitudinal grooves in the inner surface of said sleeve, a series of external longitudinal grooves in the outer surface of said sleeve the grooves of both series extending to a depth less than the thickness of the sleeve, the outer diameter of the spindle being of a dimension determined by the bore of the work piece, and means mounted on the spindle for shifting said sleeve longitudinally thereof in opposite directions to expand and contract said sleeve. said means comprising a nut threaded on said spindle and connected to said sleeve for longitudinal movement therewith but rotatable independently thereof.

6. An expansion arbor consisting of a sleeve having a series of spaced longitudinal grooves in its outer surface and a series of spaced longitudinal grooves in its inner surface, the said sleeve having portions of its outer surface at equally spaced intervals at a greater radial distance from the center than throughout the intermediate portions.

7. An expansion varbor consisting of a sleeve having a series of spaced longitudinal grooves in its outer surface and a series of spaced longitudinal grooves in its inner surface, said sleeve having three portions of its outer surface at equally spaced intervals at a greater radial distance from the center than throughout the intermediate portions.

8. An expansion arbor consisting of a sleeve having a series of spaced longitudinal grooves in its outer surface and a series of spaced longitudinal grooves in its inner surface, said sleeve having a portion of its length intermediate its ends of reduced overall diameter.

9. 'I'he combination with a spindle of an expansion arbor for creating a driving connection between said spindle and a member to be driven comprising a sleeve having spaced slots in its outer surface and spaced slots in its inner surface, the two series of slots being circumferentially staggered with respect to each other, said spindle having a tapered portion engaging the bore of said sleeve throughout a portion of its length at one end, a tapered member mounted co-axially with said spindle and engaging the bore of the sleeve at the other end. and means for shifting said spindle and said tapered member axially toward and away from each other to expand and contract said arbor.

HANS WOLLNER.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 291,282 Blue June 1, 1884 404,477 Griiiin June 4, 1889 525,645 Berner Sept. 4, 1894 1,250,532 Ulrich Dec. 18, 1917 1,343,273 Moore June 15, 1920 2,226,078 Spahn Dec. 24, 19.40

2,348,819 Johnson Mar. 16, 1944 FOREIGN PATENTS Number Country Date 113,110 Germany Aug. 30, 1900 138,050 Germany Jan. 16, 1903 OTHER REFERENCES American Machinist, page 438, May 14, 1942. 

